Chapter 5: Problem 38
Find each indefinite integral. $$ \int \frac{x^{2}-1}{x-1} d x $$
Short Answer
Expert verified
The indefinite integral is \( \frac{x^2}{2} + x + C \).
Step by step solution
01
Simplify the integrand
Before integrating, simplify the integrand \( \frac{x^{2}-1}{x-1} \). Notice that the numerator can be factored: \( x^2 - 1 = (x-1)(x+1) \). This allows us to cancel the \( x-1 \) term in the numerator and denominator, simplifying the expression to \( x+1 \).
02
Integrate the simplified expression
Now that the integrand is simplified to \( x+1 \), integrate term by term: \( \int (x+1) \, dx \) becomes \( \int x \, dx + \int 1 \, dx \).
03
Perform the integration
Integrate each term separately. For \( \int x \, dx \), the integral is \( \frac{x^2}{2} \). For \( \int 1 \, dx \), the integral is \( x \). Therefore, the indefinite integral is \( \frac{x^2}{2} + x + C \), where \( C \) is the constant of integration.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integrand Simplification
Simplifying the integrand is a crucial first step in solving an indefinite integral. In this problem, you're given the integral \( \int \frac{x^{2}-1}{x-1} \,dx \). The expression under the integral sign is called the integrand, which can often be simplified to make integration easier.
To simplify \( \frac{x^{2}-1}{x-1} \), notice that the numerator is a difference of squares: \( x^2 - 1 = (x-1)(x+1) \). By factoring the numerator, the \( x-1 \) terms in the numerator and denominator cancel each other out, leaving you with the much simpler expression \( x+1 \).
To simplify \( \frac{x^{2}-1}{x-1} \), notice that the numerator is a difference of squares: \( x^2 - 1 = (x-1)(x+1) \). By factoring the numerator, the \( x-1 \) terms in the numerator and denominator cancel each other out, leaving you with the much simpler expression \( x+1 \).
- Factoring: Look for common factors or patterns such as the difference of squares to break down expressions.
- Cancelling Out Terms: Simplify fractions by canceling common terms in the numerator and denominator, when possible.
Integration Techniques
Integration is the process of finding a function whose derivative is the given function, called the integrand. After simplifying the integrand to \( x+1 \), you can use basic integration techniques to find the indefinite integral.
For each term of the expression, apply the power rule of integration, which states:
For each term of the expression, apply the power rule of integration, which states:
- Power Rule: If \( f(x) = x^{n} \), then \( \int f(x) \, dx = \frac{x^{n+1}}{n+1} + C \) for \( n eq -1 \).
- Integrating \( x \): Using the power rule, \( \int x \, dx = \frac{x^{2}}{2} \).
- Integrating a constant (1): For any constant \( a \), \( \int a \, dx = ax \). Therefore, \( \int 1 \, dx = x \).
Constant of Integration
When solving indefinite integrals, don't forget the constant of integration, denoted as \( C \). This constant is crucial because indefinite integration represents a family of functions, each differing by a constant.
Observe that:
Observe that:
- Indefinite integrals lack specific limits or boundaries on the variable of integration. This means the inverse derivative's constant cannot be determined directly.
- Adding \( C \): After performing integration, always remember to add \( C \). For this problem, \( \int (x+1) \, dx = \frac{x^2}{2} + x + C \).